1. Field of the Invention
The present invention relates to a positioning method and a positioning apparatus, which are capable of quickly and precisely positioning or aligning even a very heavy stage apparatus for supporting a wafer, a mask, an object to be measured (e.g., a measurement object), or the like, in assemblages of a semiconductor exposure apparatus, an electron-beam drawing apparatus, a precise measuring instrument, and the like.
2. Description of the Related Art
In assemblages of an exposure apparatus for producing a semiconductor, an electron-beam drawing apparatus, a precise measuring instrument, and the like, it is required that the stage apparatus for supporting a wafer, a mask, a measurement object, or the like, be quickly and precisely positioned relative to an exposure optical system, and the like. There has been proposed a conventional positioning apparatus for performing, for example, pre-alignment of a substrate, such as a glass plate, which is to be mounted on a semiconductor exposure apparatus, an exposure apparatus for producing a liquid crystal display device, and the like, a working apparatus, or an inspection apparatus, as disclosed in Japanese Patent Application Laid-Open No. 5-109871 (1993). In such a disclosed positioning apparatus, which is illustrated in FIG. 9 of this application, when pre-alignment is executed by pressing a substrate P on a holder 103 against reference rollers 104A, 104B and 104C using two pressing rollers 104D and 104E for providing forces in two directions, respectively, pressing forces generated by the pressing rollers 104D and 104E at the time of positioning are made small, and a sensor 125 for generating a positioning-completion signal is used in order to prevent an occurrence of mechanical distortion (deformation) of the substrate P.
Further, Japanese Patent Application Laid-Open No. 7-308834 (1995) discloses, as illustrated in FIG. 10 of this application, a moving table in which guide rails 212a to 212d are fixed to a movable mount 218 and a stationary base 219, respectively, and the movable mount 218 is movably supported on balls 211.
However, the positioning apparatuses discussed above are to be used for positioning a relatively-light substrate, and it is, hence, difficult to adapt these apparatuses to the positioning of a heavy stage apparatus. More specifically, if a heavy body is moved on the holder by the pressing rollers in the apparatus shown in FIG. 9, there is a danger that its installation surface is rubbed and becomes damaged. Furthermore, since the frictional resistance is large, it is difficult to accurately press the body against the three reference rollers, so that a partially-butting condition is likely to occur.
In the latter apparatus, as shown in FIG. 10, and assuming that the movable mount is a heavy body to be positioned, its rigidity is low because the body is supported by the balls even after the positioning. Accordingly, the apparatus cannot be applied to highly-precise positioning.